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When video calls are being auto answered on the 7985 IP phone, if a call came through and was immediately auto answered, it would fail with the "No resources available" error message from the MCU

Core Issue

Video calls can take longer to complete than voice calls because there is a delay inherent in H.320 bonding. If these calls are set to auto answer, they fail. The calls do work correctly when the IP phone is set to answer manually.

Several timers in the Cisco Unified CallManager are tuned, by default, in order to make voice calls process as fast as possible. These timers can cause video calls to fail. Therefore, modify the default values of these timers in order to support H.320 gateway calls:

  • The H.245TCSTimeout
  • The Media Exchange Interface Capability Timer
  • The Media Exchange Timer


Cisco recommends that each of these timers — the H.245TCSTimeout, the Media Exchange Interface Capability Timer, and the Media Exchange Timer — be increased to 25. In order to modify the timers, go to Service Parameters in the Cisco Unified CallManager Administration.

Note: These are cluster-wide service parameters, so they affect calls to all types of H.323 devices, including voice calls to existing H.323 Cisco voice gateways.

Refer to the Gateways for Video Telephony section of Gateways, as well as Release Notes for Cisco IPVC 3511 MCU, Cisco IPVC 3511 MCU E, and Cisco IPVC 3540 MCU Module Release 3.2.224 for more information on timers and Multipoint Control Units (MCUs).

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Last update:
‎07-01-2009 01:51 AM
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